They don't even believe the size of that market will be 42M compact cars. Autonomous cars will not be privately owned and be utilized very differently than privately owned cars. And of course, Tesla is investing in that as well.

A privately owned car is useless battery capacity that is sitting there not driving and fully charged for most of the time while you are sleeping, working, or whatever (i.e. not driving). An autonomous car owned by a company that sells rides is very different. It will be ferrying around people whenever it can. You need a lot less of those to satisfy demand.

Tesla will be selling lots of vehicles and batteries before we get there of course. But it would be a mistake to think of the market in terms of how things currently work. Which is the mistake this article makes.